text: The initial and rate limiting step involving the electrophilic activation of RHC-H by a Pt center to produce a Pt-CHR species and a proton. The mechanism of this activation is debated. One possibility is the oxidative addition of a sigma coordinated C-H bond followed by the reductive removal of the proton. Another is a sigma-bond metathesis involving the formation of the M-C bond and a H-Cl or H-O bond. Regardless it is this step that kinetically imparts the chemoselectivity to the overall transformation. Stronger, more electron-rich bonds are activated preferentially over weaker, more electron-poor bonds of species that have already been partially oxidized. This avoids a problem that plagues many partial oxidation processes, namely, the over-oxidation of substrate to thermodynamic sinks such as HO and CO.
  In the next step the Pt-CHR complex is oxidized by [PtCl] to a Pt-CHR complex.  There have been multiple studies to find a replacement oxidant that is less expensive than [PtCl] or a method to regenerate [PtCl].  It would be most advantageous to develop an electron train which would use oxygen as the ultimate oxidant.  It is important that the oxidant preferentially oxidizes the Pt-CHR species over the initial Pt species since Pt complexes will not electrophilically activate a C-H bond of the alkane (although Pt complexes electrophilically substitute hydrogens in aromatics - see refs.  and  ).  Such premature oxidation shuts down the catalysis.
  Finally the Pt-CHR undergoes nucleophilic attack by OH or Cl with the departure of  Pt complex to regenerate the catalyst.